Road test: C-Leg and Rheo Knee – brothers in spirit

What benefits do computer-controlled prosthetic systems provide? For a long time, Otto Bock's C-Leg was the only microprocessor-controlled prosthetic system that worked in real time. Now, Össur has added Rheo Knee – and with it comes a promising new technology.

HANDICAP wanted to find out what benefits each of these systems offer to transfemoral amputees. Gunther Belitz has compared the two concepts and has tested both the Rheo Knee and the C-Leg in practice.

Honour where honour is due

When Otto Bock's C-Leg was first presented to the public, it marked a definite leap forward in the development of lower-limb prosthetics. The first microprocessor-controlled knee joint in the world, it was capable of regulating not just the swing phase control but also the stance phase locking across the entire gait cycle – almost in real time. Other "computer legs" that were around at the time could only control the swing phase, which meant they were always a step behind ... More than 11,000 amputees have been fitted with a C-Leg: people who thanks to it can now move around much more freely, at different speeds and without the fear of stumbling or falling over if the terrain gets more difficult.

People who can comfortably descend slopes and hills and who have learned how to go down steps, alternating with their C-Leg. In short: for thousands of upper leg amputees the C-Leg has been a decisive step towards a more natural gait and a better quality of life.The leap forward that world beater Otto Bock achieved with the C-Leg is demonstrated on the one hand by the fact that for eight years this system was the only one of its kind on the market, and was clearly at the forefront of technology in lower-limb prosthetics. On the other hand it had taken at least that long before the C-Leg became a marketable product. The original idea came from a Canadian biomechanical engineer, Kelvin James, who had been developing prototypes at the University of Alberta since 1986. Then, in 1992, Otto Bock bought the computerized knee from him. Thanks to the efforts of the brain pool at the "Wiender Dependence" (Duderstädter group of companies) this prototype for an artificial limb then matured into the so-called C-Leg.